Identifying
and Preventing Vole Damage

Introduction

As the deep
snows in our yards or on our properties recede, you may be greeted
by one or more pathways in the snow (see photo). If you’re lucky,
these paths only run from one burrow opening to another. Unfortunately,
some of the trails probably lead to some of your favorite trees and
the damage caused by the animals girdling (gnawing the bark off all
the way around the plant) the tree will kill it.

The furry culprit in this
destruction? The vole.

Also known as meadow mice,
these small, stocky short-tailed rodents can cause severe damage in
landscape, orchard, windbreak or timber plantings. They measure from
4 to 8.5 inches long and vary in color from brown to gray. They are
pudgy, with blunt faces and small eyes, small and sometimes inconspicuous
ears, short legs, and a short and scantily haired tail (the long-tailed
vole is an exception).

Voles are active day and
night throughout the year. They usually live 2 to 16 months. Voles
construct many surface runways and underground tunnels with many burrow
entrances.

Voles are extremely prolific,
having three to six young per litter and three to 12 litters per year.
Females may become pregnant at three weeks of age and voles breed
almost year round. Large population fluctuations ranging from 14 to
500 voles per acre are common.

Most vole damage occurs
in the winter when voles move through their grass runways under protection
of snow or where there are thick, tall grasses and weeds. Heaviest
vole damage seems to coincide with years of heavy snowfall.

Damage and Control

Vole damage to trees and shrubs is characterized by girdling and patches
of irregular gnaw marks about 1/16 to 1/8-inch wide. Gnawed stems
have a pointed tip. Do not confuse vole damage with damage by rabbits,
which includes stems clipped at a smooth 45-degree angle and wider
gnaw marks. Stems browsed by deer usually have a rough jagged edge.
Voles also girdle the roots of trees and shrubs.

Other signs of voles being
present include: 1) 1- to 2-inch wide runways through matted grass
and burrows; 2) visual sightings; 3) hawks circling overhead and diving
into fields; and 4) spongy soil from burrowing activity. Trees that
appear to be suffer from disease or insect infestation may be suffering
from unseen vole damage.

Methods to prevent and
control vole damage are habitat management, exclusion, repellents,
trapping and poison baits. Voles are non-game animals in Colorado
and may be captured or killed when they create a nuisance or damage
property.

Habitat Management

Elimination of ground cover including weeds and tall grasses by frequent
close mowing, tilling or herbicide application is the most successful
and longest lasting method to reduce vole damage.

Other methods include:

Plant short grasses
that do not mat or lodge such as buffalograss or blue grama. These
will provide little protective cover and may reduce vole numbers.

Little data are available on effectiveness of repellents to deter
vole damage. There are a variety of commercial repellents labeled
for protecting tree seedlings, shrubs, ornamental plantings, nursery
stock, and fruit trees from voles. Check with nursery supply stores

Capsaicin (Hot Sauce Animal
Repellent, Miller Chemical and Fertilizer Corp.) is labeled to protect
various woody plantings from voles. The following home made repellent
has also proven to be quite effective in keeping most animals away
from given areas and plants. It must be reapplied after three to five
days.
Hot Pepper Repellent Recipe
• One chopped yellow onion
• One chopped jalapeno pepper
• One tablespoon cayenne pepper

Boil ingredients for 20
minutes in two quarts of water. Let the solution cool and then strain
through cheesecloth. You can apply this with a tank-type sprayer or
a spray bottle.

Another home made repellent
that has been shown to be effective in reducing deer and elk browsing
and may reduce vole damage.
20% Chicken Egg Repellent
A spray of 20% whole eggs and 80% water is effective, but to keep
the sprayer from clogging, remove the chalaza or white membrane attached
to the yolk before mixing the eggs. The egg mixture is weather resistant
but must be reapplied in about 30 days.

Trapping

Use mouse snap traps to remove small populations of voles from lawns.
Place traps perpendicular to runways with the trigger mechanism in
the runway and bait the trap with small amounts of peanut butter or
a mixture of peanut butter and rolled oats. Set traps in the fall
before most damage occurs.

Toxic Baits

Rodenticides are a short-term solution to damage by voles. Habitat
management usually is more successful than rodenticides for eliminating
damage, particularly in orchards. Two percent zinc phosphide is the
only legal grain bait in Colorado. It is a restricted use pesticide,
so only certified applicators can use this material.